In this work, the structural, electronical and optical properties of diimine−dithiolate complexes with the general formula [M(bpy)(dithiolate)] (M = Ni, Pd, Pt ; dithiolate = 1,2-benzenedithiolate (bdt), 4-cyanobenzene-1,2-dithiolate (cbdt), 3,4-toluenedithiolate (tdt), pyrazine-2,3-dithiol (pdt), 2,5-dicyano-2,3-dithiolatepyrazine (dcdmp), quinoxaline-2,3-dithiol (qdt)) are studied by using density functional theory (DFT) calculations. The geometry of latter complexes was fully optimized at B3LYP level of theory using the G09 program. The 6-31G* basis set is used for H, C, N, O and S atoms (all light atoms), and also the LanL2DZ basis set for Ni, Pd and Pt atoms. The time-dependent density functional theory (TD-DFT) calculations have been performed to consider optical properties at the same level of theory associated with the polarized continuum model (PCM). The bond length, bond angle, thermodynamic parameters, NBO charges, binding energies, frontier orbital energies (HOMO and LUMO), band gap (Eg), absorption spectra in gas and solvent phases, oscillator strength and light harvesting efficiency (LHE) are explored. The calculated M-N and M-S bond lengths increase with the trend Pt ≈ Pd > Ni, while we do not observe any significant difference between the geometrical parameters for the complexes with different dithiolate substituent. The optimized geometries show that the metal atom is coordinated by two N atoms of the bipyridine ligand and two S atoms of the dithiolate ligand forming a slightly distorted square planar geometry with the two five membered rings (MS2C2 and MN2C2). Thermodynamic analysis indicates that all of the binding energies are negative, and it seems that the Pt(II) complexes are thermodynamically stable. The calculated NBO charge distribution indicates that the metal atoms always carry a positive charge, while the nitrogen and sulfur atoms carry a negative charge. Also, nitrogen is significant more negative charged than sulfur. Therefore, there is a decrease in the charge distribution on the metal and dithiolat ligand reflecting charge transfer from the dithiolate to the metal and bipyridine ligand. In continue, the effect of electron donor and electron acceptor substitutions such as CH3, Ph and CN- on the HOMO-LUMO energy levels and electronic band gap (Eg) of complexes are considered. Results show that the CN- substitution on the phenyl ring dithiolate ligand has a favorable effect on the electronic properties. Comparison of the calculated absorption spectra in dichloromethane solution with those in gas phase show that the solvatochromic effect. The charge-transfer bond of complexes stretches from 400 to 600 mainly corresponded to the transition of the HOMO to LUMO or mixed HOMO-1 to LUMO, which can be consider mixed metal–ligand to ligand charge transfer (MMLL´CT) transitions. Also, an intense band in the UV regions at approximately 300 nm can be assigned to the intraligand transition of the bpy ligand (π→π*). The absorption in the visible region with the highest oscillator strength of the electromagnetic spectrum is well within the acceptable range required for dye-sensitized solar cells (DSSC). As a result, the changing of dithiolate ligand has more effect on the transition energy and the changing of metal ions enhances more the oscillator strength.

In this project, the non-symmetric phosphorous ylide metanitrobenzoyl  methylen diphenyl-diphenyl¬phosphino¬methyl phosphorane (L), were prepared and characterized by elemental analysis, FTIR, ¹H NMR, ¹³C NMR and ³¹P NMR spectroscopies. The new complexes of mercury(II) and paladium(II) characterized by elemental analysis, IR, ¹HNMR, ¹³CNMR and ³¹PNMR.The spectral data indicate that the bidentat coordination of the ligand (L) through both phosphine group and ylidic carbon atom. The antitumor activity of entitled ligand and paladium(II) complex has been evaluated using the MTT and TBA assay on Caco-2 cells line (colon cancer). The ligand and related complexes are as follows:

(L) [Ph₂PCH₂PPh₂C(H)C(O)C₆H₄NO₂]
(1) [(Ph₂PCH₂PPh₂C(H)C(O)C₆H₄NO₂) HgCl₂]
(2) [(Ph₂PCH₂PPh₂C(H)C(O)C₆H₄NO₂) HgBr₂)] 
(3)   [(Ph₂PCH₂PPh₂C(H)C(O)C₆H₄NO₂) HgI₂)] 
(4)  [(Ph₂PCH₂Ph₂PC(H)C(O)C₆H₄NO2)PdCl₂] 

Abstract
Name: Salman Surname: kordi
Title:
Synthesis and characterization of new stabilized phosphonium–phosphine ylide derived from bis(diphenylphosphino)ethane and its complexes with Hg(II) and Pd(II).
Supervisor: Dr. Sepideh Samiee
Degree: M.Sc.
University: Shahid Chamran University
Department: Chemistry Faculty: Science
Keywords: Phosphonium- phosphine ligand،Hg(II) complex, Pd(II) complex, antitumor activity
In this project, the asymmetric Phosphorous ylide metanitrobenzoyldiphenyl-2- diphenylphosphinoethyl phosphorane (L), was prepared and characterized by elemental analysis, IR, 1HNMR, 13CNMR and 31PNMR spectroscopy. The new complexes of Hg(II) and Pd(II) metal ions were obtained from this asymmetrical phosphorous ylide and characterized by elemental analysis, IR, 1HNMR, 13CNMR and 31PNMR. The spectral data indicate the formation of the P- coordinated bonding modes in Hg(II) complexes and the P,C- coordinated bonding modes for Pd (II) complex. The antitumor activity of the ligand (L) and the complex (4) has also been evaluated using the MTT and TBA assay on Caco-2 cells line (colon cancer). The above mentioned ligand and their complexes are as follows:

(L) ] [Ph2PCH2CH2PPh2C(H)C(O)C6H4NO2
(1) [(Ph2PCH2CH2PPh2C(H)C(O)C6H4NO2) HgCl2]
[(Ph2PCH2CH2PPh2C(H)C(O)C6H4NO2) HgBr2)] (2)
[(Ph2PCH2CH2PPh2C(H)C(O)C6H4NO2) HgI2)] (3)
[(Ph2PCH2CH2Ph2PC(H)C(O)C6H4NO2)PdCl2] (4)

 

In this research, the reaction of phosphine–phosphonium salts, [PPh2CH2CH2PPh2CH2C(O)C6H4R]Br (R = Br (S1), NO2 (S2), with mercury(II) halides in dry methanol yielded the zwitterionic complexes {HgX2Br(PPh2(CH2)2PPh2CH2C(O)C6H4R)} [R = Br: X = Cl (1), Br (2), I (3); R = NO2; X= Cl (4), Br(5), I(6)]. These complexes were fully characterized by elemental analyses, IR, 1H, 13C, and 31P NMR spectroscopies. In addition, the crystal structure of complex 4 was determined by X-ray crystallography. The single crystal X-ray analysis confirms the presence of Hg–P bond and also reveals a distorted tetrahedral geometry around the mercury atom.